Upavasa

Upavasa literally, abstaining from food, applies to Hindu fasting. Most religions have some form of fasting when people abstain from eating and drinking to exercise control of the senses and to acquire a sense of closeness with the divine. Hinduism too has a form of fasting for both physical and spiritual benefits. Unlike Muslim fasting which is obligatory during the month of ramjan, Hindu fasts are observed only on several different occasions: weddings, pujas and various religious rites
Some Hindus regularly observe weekly fasts, believing that this regimen keeps them healthy. In their case the physical aspect is more important than the spiritual. Those who fast for religious reasons believe that physical as well as mental abstention from pleasures is necessary. Fasting thus also plays a role in controlling desire, anger, greed and lust. It is believed that a devotee who exercises restraint through fasting can enjoy profound mental peace. Hindus fast on certain regular days, for example, on a fixed weekday, on the eleventh day of the lunar fortnight, on amavasya, the last day of the lunar moon, or on purnima, the day of the full moon. Devout Hindus also fast before a puja or other religious rites. Hindu students fast before worshipping the goddess saraswati, the goddess of learning.
Unlike the Muslim fast, which lasts from sunrise to sunset, upavasa is a twenty-four hour fast. However, unlike the Muslim fast which does not allow any food or drink for the duration of the fast, during upavasa water may be drunk and something light, for example, fruit or khoi, puffed rice, may be eaten. Among Muslims, the obligatory fast in Ramadan is binding on both men and women. However, among Hindus, certain fasts are observed by both men and women, some only by women, while others by men alone. For example, when a girl gets married, her father is obliged to observe upavasa, while the mother may or may not do so.
The severity of upavasa varies, depending on a person's physical condition and capacity for endurance. Those who cannot fast for the entire 24-hour period without eating something may take a small quantity of light food. For example, a prospective bride's father may take khoi-though not moori-and water during his fast. On the other hand, someone may decide not to take even water during upavasa. Some great sages are known to have observed upavasa for two, three, or even four days at a stretch. MK Gandhi used the tradition of fasting for political purposes.